The Friday order, signed by U.S. Magistrate Judge Paul Grewal, requires Ellison and Page to meet on Sept. 19 and be prepared for further conferences between Sept. 20 and Sept. 30. The suit is scheduled to go to trial on Oct. 31.

Grewal also ordered lawyers from each company to attend a pre-conference tutorial next week.

Oracle had initially proposed sending its president, Safra Catz, to the mediation, and Google had hoped to send Andy Rubin, who heads its mobile business. Oracle objected to Rubin, and the judge objected to both proposals, instead recommending the CEOs.

However, the fact that the judge wanted the CEOs to attend the mediation indicates that he believes a lot is at stake, said patent expert Florian Mueller. "He previously said that this lawsuit could cost Google billions, and if he didn't believe at this (even more advanced) stage that there's a whole lot of money at stake, he would probably be fine with negotiators who don't have the ultimate decision-making authority (except for board approval) in their organizations," Mueller wrote in a blog post when Alsup first recommended Ellison and Page.

The companies are battling over the way in which Google's Android handles Java applications. Oracle accuses Google of copying parts of Java in Dalvik, the virtual machine in Android that runs Java applications. Google denies wrongdoing.